1. Field of Invention
The present invention relates to lithium phosphate thin film and method for manufacturing the same. More particularly, the present invention relates to an electrochemical method for manufacturing lithium phosphate thin film.
2. Description of Related Art
Lithium ion secondary battery has been widely used in consumer electronics and high power electronics because it is light in weight, high in electromotive force, and high in energy density. Lithium ion secondary battery includes high power lithium battery, high capacity lithium battery, and thin film lithium battery. Thin film lithium battery is thin, flexible, and printable can be used as a flexible driving power source for IC card, flexible electronic devices and medical electronics.
Thin film lithium battery includes solid-state thin film battery and organic radical battery. Solid-state thin film battery employs lithium phosphorus matrix (metal- or nitrogen-doped Li3PO4) thin film as solid electrolyte and thus has many advantages over other lithium secondary batteries. First, solid electrolyte of solid-state thin film battery does not exhibit the problem of electrolyte leakage of liquid electrolyte. Besides, the thickness of solid-state thin film battery is less 10 μm and thus can be manufactured into any desirable size and shape. Moreover, solid-state thin film battery has high power density and excellent charge/discharge cycle performance.
Presently, lithium phosphorus matrix thin films are manufactured by physical sputtering techniques such as RF magnetron sputtering. However, in most sputtering systems, the deposition rate is slow. For example, in RF magnetron sputtering, the deposition rate is about 170 Angstroms per minute. In other words, it cost nearly an hour to obtain a film with 1 μm thickness. The long processing time per deposition cycle leads to high manufacturing cost of solid electrolyte.
In view of the foregoing, there is a need to provide a method for manufacturing solid electrolyte that is faster and simpler than prior art.